Online video startup NimbleTV told us that service was just months away, and it's acting on that promise with the official launch of its private beta. The 250-plus New York City residents let into the beta will have the option to stream cable, satellite or other paid TV services to virtually any device with a modern web browser and a good broadband connection. Regular service could be available in the first quarter of 2013 at an estimated $20 per month, although this doesn't include the TV programming in question: NimbleTV's business model requires subs